This invention relates to a curvature control device for elevating the end section of an endoscope which is inserted into a part to be examined. The specific features of the invention reside especially in the control of the amount of play in curving the end section and in a curvature operation range control mechanism thereof.
In general, in a curvature control device for an endoscope of this type, the aforementioned end section is coupled through two wires to a mannual operating section, and the end section is curved to either side by selectively pulling one of the two wires. In this case, the other wire must extend or contract depending on the curvature of the end section. Therefore, there must be provided an idle mechanism between the wires and the operating mechanism in order to absorb the difference between the amount of wire movement and the amount of the pulling operation.
On the other hand if, with respect to the movement of the wire which is tightened by being pulled in order to determine the direction and degree of the curvature of the end section, there is play in the pulling operation due to the wire tension, the delicate sense of the operator's hand is affected, which may lead to erroneous operations such as for instance a mistake in finding the part to be examined. Accordingly, the play must be minimized.
There are some devices which have been improved so as to meet the various requirements for eliminating the above-described difficulties. However, even with such improved devices, the wires are liable to be lengthened and the relevant operating members are deformed by repeatedly using the devices for a long time. Therefore, the actual amount of movement of the wire is liable to be changed over a period of time when compared with the amount of movement thereof obtained when it was initially used. Therefore, it is necessary to eliminate the amount of play by adjusting the relevent mechanisms when required.
If the wire has play (the actual amount of movement of the wire is decreased by the lengthening of the wire), with the operation range of the operating member preset the curvature range of the end section is decreased, the observation range is also decreased, and it may be difficult to sample desired cells. Accordingly, adjustment of the operation range of the operating member is necessitated to eliminate the play which is caused by using the device for a long time.
In the case of the conventional device of this type, in order to eliminate the play which is caused by the use of the device, a method in which the length of the wire is shortened or the coupling positions and angles between the operating knob and the movable members are readjusted, that is, a method of disassembling the relevant mechanisms, is employed. This work is difficult and troublesome.